AR Technologies
Compiled By Alem Fitwi
Sunnyvale, CA, USA
April 2022
Src: Internet, Optics Conferences & Old Notes
from IPython.display import Image
Image("./Figs/wg1.png")
Fig 1: Propagation of EMWs Via A WG
Bragg Reflection Law: this law simply states that when the X-ray is incident onto a crystal surface, its angle of incidence is $\theta$ and it is reflected back with the same angle of scattering $\theta$. And if the path difference $d$ is equal to a whole number $n$ of wavelength, constructive interference will occur.
$$nλ=2dsinθ$$
$$2n\Lambda sin(\theta + \phi ) = \lambda_B$$
Collimation: the accurate adjustment of the line of sight of a telescope. Type of adjustment, readjustment, or registration. The act of adjusting something to match a standard.
Calibration: the process of configuring an instrument to provide a result for a sample within an acceptable range. Eliminating or minimizing factors that cause inaccurate measurements is a fundamental aspect of instrumentation design.
Thin Lens Equation:
Binning: The process of downsampling an image by creating a set of super pixels. It is a tradeoff between read-noise and spatial resolution.
OLED: The acronym 'OLED' stands for Organic Light-Emitting Diode - a technology that uses LEDs in which the light is produced by organic molecules. These organic LEDs are used to create what are considered to be the world's best display panels.
Image("./Figs/wg2.png")
Fig 2: Optical Design Of Exsiting/Old Headset VRs
Image("./Figs/wg3.png")
Fig 3: Projection of collimated virtual Image Via WG From An OLED or $\mu LED$ Display To An Eyebox/Output Grating using a flat mirror.
Image("./Figs/wg4.png")
Fig 4: Projection of collimated virtual Image Via WG From An OLED or $\mu LED$ Display To An Eyebox/Output Grating using a curved mirror.
Image(("./Figs/wg5.png"))
Fig 5: VH-FOV
Image(("./Figs/wg6.png"))
Fig 6: Diffractive WG (Nokia Surface Relief WG)
Image(("./Figs/wg7.png"))
Fig 67: Holographic WG
Image(("./Figs/wg8.png"))
Fig 8: Polarized Reflective WG (Early Lumus Prototype WG)
Image(("./Figs/wg9.png"))
Fig 9: Reflective WG
Major Components of an AR Glass Eye Wear:
Glasses Frame: Holds the whole set of components together.
Battery (typically LiPo Battery): Source of Electrical power
$\mu$LED Display (DPA) $\rightarrow$ Source of Virtual Image. It generates the virtual image.
Optical Engine/Projector Module: Performs Light Beam Collimation and Projects the virtual image produced by the $\mu$LED towards the entrance aperture of the WG.
WG: performs 2D pupil expansion and propagates the image towards the Input Grating.
Input Grating: Receives the projected lights (the projected & collimated virtual image) and sends it to Fold Grating.
Fold Grating: Receives light rays reflected by the Input Grating via the WG and send them to the eyebox or output grating.
Output Grating/Eyebox: Sends the virtual image in parralel to the eye balls. The light rays come to our eye balls in parallel; as a result, the image appears as if at infinity.
Lens: The most complicated technology is in the lenses for both dispersing and focusing light rays
Camera: For taking pictures
Bluetooth: For communication with Mobiles, Laptops, or other blutooth protocol supporting devices
Image(("./Figs/wg10.png"))
Fig 10: Eyebox/Output Grating On The Glass Frame
Image(("./Figs/wg11.png"))
Fig 11: Nano Precision Optical Structures (Input Grating, Fold Grating, and Output Grating)
Out of the millions of possible beam interactions, only a subset of them contribute to the image sent to the eyebox.
Hence, through the application of a Reverse Tracing on the image light rays on the user eyebox, it is possible to pin point the exact ouput Fold and Input Diffractive Grating Regions that actually contribute to the images seen from the within the eyebox.
An example that shows how corrections by way of Reverse Ray Tracing and advanced optics are illustrated in the figure below.
1 2 3
IG 4 5 6
7 8 9 9 8 7
OG 6 5 4
9 6 3 3 2 1
FG 8 5 2
7 4 1
Image(("./Figs/wg12.png"))
Fig 11: Reverse Light Ray Tracing To Determine The Subsets of Rays Contributing to The Formation of the V-Img On The Eyebox
"With Patience We Can Dissect An Ant And Reach Its Heart"
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